PHYSIOLOGICAL RESPONSES OF DIFFERENT GRAPEVINE GENOTYPES (VITIS SPP.) TO VARIABLE TEMPERATURES ARTIFICIALLY ESTABLISHED AS CLIMATE CHANGE SCENERY

Abstract

Extremes in temperature resulting from global warming significantly threaten agriculture worldwide. Obtaining reliable information about the unique response of cultivars to changing environmental conditions can help employ precision practices for better plant physiology and growth.Researches on the effect of high temperatures on vines have generally focused on characteristics such as phenology, growth, yield, and fruit composition. Experimental knowledge about the effects of high temperatures on vine physiology largely remains insufficient. In this study, physiological responses of three different grapevine genotypes [‘Michelle Palieri’, ‘Black Magic’ and the rootstock 41 B (Vinifera × Berlandieri)] to three different temperature conditions were established using glasshouses and open vineyard. The conditions were (I) optimum temperature (OT, maintaining a day time average of 25±2 °C), (II) low temperature (LT, maintaining a day time average of 17±2 °C), and (III) high temperature (maintaining a day time average of 33±2 °C) during the study period. OT and HT conditions were established by using two different climate controlled glasshouses while LT occurrednaturally under the temperate zone condition of open vineyard. The highest gs values were always determined under OT condition, while the gs values were far below the literature at LT and HT conditions for all genotypes. Leaf temperature consistently increased with the increase in environmental temperature across the grapevines.The soil temperature around the efficient root zone was as high as 29.7°C, around the upper threshold level of the optimum photosynthesis for grapevines, while the soil temperatures for other conditions were in recommended levels.The general findings revealed that the different temperature conditions directly affected the physiology of the grapevines with adverse effects of high or low temperatures outside the optimum levels. 41 B showed higher sensitivities to changing temperatures than those of V. vinifera cultivars. Differential responses of the genotypes revealed the importance of the use concrete and more stress tolerable cultivar to cope with the constrains of the climate change on viticulture.